Selective code receiver



Jufly 3%, 1934. H. E. HERSHEY SELECTIVE CODE RECEIVER Filed May 17, 1929UNITED STATES PATENT OFFICE SELECTIVE CODE RECEIVER Harry E. Hershey,0akPark, Ill., asslgnor, by mesne assignments, to Associated ElectricLaboratories, Inc., Chicago, 11]., a corporation of Delaware ApplicationMay 17, 1929, Serial No. 363,875

1 Claims.

The present invention relates in general to improvements in selectivecode receivers. The main object of the invention is the design of areceiving device which may be used in conjunction with wirelessreceiving apparatus and which will respond to and record only apredetermined signal such as an S. O. S. distress call.

A particular feature of the invention is the provision of a chain ofcounting relays which is completely operated only by the S. O. S. signalof three dots, three dashes, and three dots.

Another feature of the invention lies in the system of control relayswhich discriminate between the dots and dashes of a received signal.

Another feature is the provision of means for restoring the receiver tonormal in case the entire signal is not received as a single letter.-

A still further feature of the invention lies in the means for releasingthe operated portion of the relay chain at any point during therecording of the signal if the dots and dashes of the signal are notreceived in proper number and sequence.

Other features pertaining to the detailed circuit arrangement will beapparent from the following specification.

A complete understanding of the invention may best be had from thefollowing detailed explanation when read in connection with theaccompanying drawing, comprising one figure only, which shows by meansof the usual schematic diagram the complete circuit of the S. 0. S.receiver. The wireless receiving set has been indi cated at RS and notshown in detail, as these receivers are well known in the art. Thereceiver is arranged to be used with any of these sets having a platecircuit suitable for operating the plate relay P. This plate relay maybe adjusted to operate with the particular set to be used. The minorswitch M is the standard ten-point minor switch well known in automatictelephony.

As is well known in the art, acomplete S. O. S. signal is transmitted asone letter, and the operation of the receiver depends upon the correcttransmission of the signal in accordance with this practice. A distinctpause such as is used to separate the letters of the word in telegraphywill allow the receiver to release. However, the dashes of the signalmay be made as long as desired by the operator transmitting the signalwithout interfering with the operation of the receiver in any way.

The complete'operation of the receiver upon the receipt of an S. O. S.signal of three dots, three dashes, and three dots will first beexplained. The first dot of the signal is received by the receivingapparatus RS, which in turn momentarily operates plate relay P. At itsmake contact 9, relay P closes an obvious circuit for relays 2 and 3 inmultiple. Relay 3 is slow to operate and is adjusted to respond to thedash impulses of the signal but will not respond to the dot impulses.Relay 2 operates and at contact 10 closes an obvious circuit for relay 1which is made slow to release and is adjusted to remain operated duringthe complete signal, provided the entire signal is received as a singleletter. Relay 2' also closes a circuit from ground, contact 11,resistance 12, winding of relay 4, back contact 13 of relay 3,resistance 14, to battery. Relay 4 operates but is quickly released dueto the opening of contact 11 of relay 2 which is deenergized at the endof the dot impulse by the release of the plate relay P. Before relay 4releases, however, it closes a circuit from battery resistance 14, backcontact 13 of relay 3, winding of relay 4, resistance 12, contact 15,resistance 16, winding of relay 5, to ground. Relay 5 operates in thiscircuit after relay 2 releases to remove at its armature 11 the shuntaround relay 5 and at contact 17 short circuits the winding of relay 4.

The operation of relay 5 also closes a circuit from ground, make contact18 of relay 5, conductor 95, back contact 19 of relay 21 of dot group#1, winding of relay 20, to battery. Relay 20 operates and at contact 40closes a circuit from battery, winding of relay 20, contact 40, windingof relay 21, back contact 78 of relay 6, back contact 62 of relay 26,back contact 77 of relay 6, back contact 58 of relay 32, make contact ofrelay'l, to ground. When relay 5 releases due to the opening of contact15, the ground shunt is re-' moved from the winding of relay 21,allowing it to operate in series with relay 20 in the abovetracedcircuit. At contact 41 the impulsing lead 95 is extended to relay 22 ofdot group #2.

When the second dot of the S. O. S. signal is received by the receivingset RS, relay P is again momentarily energized and in turn causes themomentary energiz'ation of relays 2, 4, and 5 in the above-describedmanner. The closing of contacts 18 of relay 5 completes a circuit fromground, contact 18, impulse lead 95, contact 41 of relay 21, contact 43of relay 23, winding of relay 22, to battery. Relay 22 operates'and atcontacts 42 105 closes a circuit from battery, winding of relay 22contact 42, winding of relay 28, to ground at contact 80 of relay 1 overthe same path as'heretofore traced for the operation of relay 21. Uponthe release of relay 5, relay 23 operates and at contacts 44 extends theimpulsing lead 95 to re lay 24 of dot group #3.

The third dot of the S. O. S. signal is received in the same manner asdescribed for the first and second dots. In this case relays 24 and 25of dot group #3 are operated. At its contact 47 relay 25 transfers theimpulsing lead 95 to relay 32 of dot group #4. At contact 59 it closes alocking circuit for the relays of the first three dot groups independentof contact 62 of relay 26. This locking circuit extends from ground,contact 80 of relay 1, back contact 58 of relay 32, back contact 77 ofrelay 6, contact 59 of relay 25, to the windings of relays 25, 23, and21 in multiple. The first three dots of the S. O. S. signal have nowbeen received and registered.

When the first dash of the signal is next received, relay P againoperates and in this case remains operated a sufiicient length of timeto operate relay 3 in multiple with relay 2. At its back contact 13,relay 3 opens the circuit of relays 4 and 5 to prevent the operation ofthese relays and the registering of another dot at this time. At contact79 relay 3 closes a circuit from ground, contact 79, conductor 96, backcontact '64 of relay 27, winding of relay 26, to battery. Relay 26operates and at contact 63 closes a circuit from battery, winding ofrelay 26, contact 63, winding of relay 27, back contact 76 of relay 6,contact 80 of relay 1, to ground. At the end of the dash impulse relay 3releases due to the opening of contact 9 of relay P and at contact 79removes the ground shunt from relay 27, allowing it to operate in serieswith relay 26 in the abovetraced circuit. At contact relay 27 extendsthe impulsing lead 96 to relay 28 of dash group #2. The second dash ofthe signal operates relays 28 and 29 01? dash group #2 in the samemanner as described above for the operation of relays 26 and 27.- Relay29, at its contact 68, extends the impulsing lead 96 to relay 39 of dashgroup #3.

When the third dsah ofthe signal is received,-

relays P and 3 operate as heretofore described.

. Relay 3 now closes a circuit from ground, con

'. will be explained later.

tact 79, conductor 96, contact 65 of relay 27, contact 68 of relay 29,back contact 71 of relay 31, winding of relay 30, to battery. Relay 30operates and at contact prepares a circuit for relay 7 as will bedescribed later. At contact 69 a circuit is closed from battery, windingof relay 30, contact 69, winding of relay 31, back contact 76 of relay6, contact 80 of relay 1, to ground. When ground is removed from theimpulsing lead 96 due to the release of relay 3 at the end of the dashimpulse, relay 31 operates in series with relay 30 in the above-tracedcircuit. At contact 72 the impulsing lead 96 is extended to relay 38 ofdash group #4. The function of. relays 38 and 39 of dash group #4 Atcontact relay 31 closes a locking circuit for the relays of the firstthree dot groups independent of contact 58 of relay 32 of dot group #4.This locking circuit extends from ground, contact of relay 1, contact 60of relay 25, contact 75 of relay 31, contact 78 of relay 6, to thewindings of relays 21, 23, and 25 in multiple. The first three dots andthe three dashes of the S. O. S. signal have now been re ceived andregistered.

When the fourth dot of the S. O. 8. signal is next received, relay Poperates and in turn operates relays 2, 4, and 5 in the manner already.

32, to battery. Relay 32 operates and at contact 48 closes a circuitfrom battery, winding of relay 32, contact 48, winding of relay 33,contact 80 the signal is received, relays 34 and 35 of dot group #5 areoperated. in the same manner as relays 32 and 33 of dot group #4. Theoperation of relay 35 extends the impulsing lead 95 to relay 36 of dotgroup #6.

When the last dot of the S. O. S. signal is received, relays P, 2, 4,and 5 operate in the same manner as heretofore described. The operationof relay 5 closes a circuit from ground, contact 18, impulse lead 95,contact 41 of relay 21, contact 44 of relay 23, contact 47 of relay 25,con tact 50 of relay 33, contact 53 of relay 35, back contact 55 ofrelay 37, winding of relay 36, to battery. Relay 36 operates and closesa circuit from battery, winding of relay 36, contact 54, winding ofrelay 37, contact 80 of relay 1, to ground. When ground is removed fromthe impulse lead 95 due to the deenergization of relay 5 at the end ofthe dot impulse, relay 37 operates in series with relay 36 in theabove-traced circuit. At contact 57 it closes ,a circuit from ground,contact 80-of relay 1, contact 70 of relay 30, contact 57 of relay 37,contact 84 of relay 8, winding of relay 7, to battery. Relay 7 operatesand at contact 81 closes an obvious circuit for the stepping magnet 86of the minor switch M. Magnet 86 operates and moves wiper 88 to thefirst bank contact 89. This closes a circuit from ground, wiper 88, bankcontact 89, alarm lamp 90, to battery, lighting the lamp to indicatethat an S. O. S. signal has been received. The pause following thetransmission of the complete S. O. S. signal allows relay 1 to releaseand open its contact 80, thereby removing ground from the holding leads,and allowing all the relays of the receiver to restore to normal. I

It will be appreciated that there is a remote possibility of impulsesdue to static being received in combination with telegraph signals inthe proper sequence and number to operate the chain of the registeringrelays. In view of this possibility, the first three bank contacts ofthe minor switch M are connected only to a lamp 90. Thus the first threesignals received will bring in only a visual alarm. The remaining bankcontacts, 4 to 10 inclusive, are wired to a lamp 91 and also to a bell92. Allowance is thereby made for a maximum of three possible falsealarms during the time that the operator is on duty. Should an S. O. S.call be received during this period, the minor switch M will be steppedpast the fourth bank contact due to the continuous repetition of thesignal. Thus an audible alarm will be sounded calling the operator toduty. The minor switch may be released by the operator at any time bydepressing the non-locking release key 94, there by closing an obviouscircuit for the release magnet 87.

Th anner in which the relay chain is automatically released should thereceived signal deviate at any point from the prescribed S. O. S. signalof three dots, three dashes, and three dots will now be explained. Itwill first be assumed its that the entire S. O. 8. signal is nottransmitted as one letter, but that a pause occurs at some point betweenthe impulses of the signal. In this case the pause will allow relay 1 torelease, opening contact 80 and thereby removing ground from the lockingcircuits of the relay-chain. This allows all relays to release and thereceiver to restore to normal.

It will now be assumed that a dash is received before the first threedots of the signal have been registered. In this case the dash impulseoperates relays 26 and 27 in the manner already described. The operationof relay 26 opens contact 62, thereby removing the holding ground fromthose relays of the dot recording group which have already beenoperated. This allows the relays of the dot recording group to bereleased. The relays 26 and 27 are maintained operated until the end ofthe signal when the usual pause will release relay 1 and restore thereceiver to normal.

If four successive dots should be received before the first dash of thesignal is received, the fourth dot will operate relays 32 and 33 in amanner already described. The operation of relay 32 opens contact 58,which removes the holding ground from the relays of the first three dotgroups, allowing them to release. In this case relays 32 and 33 aremaintained operated until the end of ,the signal when the usual pausewill allow relay 1 to release, thereby restoring the receiver to normal.The next possibility to be considered is that of a fourth dash beingreceived after the first three dots and the three dashes of the signalhave been registered. The receipt of the fourth dash will operate relaysP and 3 in the same manner as already described for the first threedashes. The operation of relay 3 closes a circuit from ground, contact79, contact 65 of relay 27, contact 68 of relay 29, contact 72 of relay31, winding of relay 38, to battery. Relay 38 operates in this circuitand at contact 73 closes a circuit from battery, winding of relay 38,contact 73, winding of relay 39, contact 80 of relay 1, to ground. Whenground is removed from the impulse lead 96 at the end of the dashimpulse, relay 39 operates in series with relay 38 in the above-tracedcircuit. At-contact 74, an obvious circuit is closed for theslow-to-release relay 6. Relay 6 operates and at contact 76 removeshold-- ing ground from the relays of the first three dash groups? Atcontacts 77 and 78 relay 6 removes holding ground from the relays of thefirst three dot groups and all relays of the first three dot groups andthe first three dash groups are thereby released. Relays 38 and 39 aremaintained energized until the end of the signal when the usual pauseallows relay 1 to release, thereby restoring the receiver to normal.

The-only other possibility which might tend to bring ina false alarm isthe receipt of a signal consisting of three dots, three dashes, and fourdots. Upon the receipt of the sixth dot, contact 57 is closed, therebyclosing a circuit for relay 7 as already described. However, the receiptof the seventh dot places ground on the impulse lead 95 which extendsthrough contact 41 of relay 21, contact 44 of relay 23, contact 47 ofrelay 25, contact 50 of relay 33, contact 53 of relay 35, contact 56 ofrelay 37, winding of relay 8, to battery. As relay 7 is made slow tooperate, relay 8 is energized in this circuit and opens contact 84before relay 7 has had time to energize. "Relay 8 closes a lockingcircuit for itself extending from ground, contact 80 of relay 1, contact.76 of relay 6, resistance 82, contact 83 of relay 8, winding of relay8, to battery. Relay 8 remains locked in this circuit until the receiveris restored to normal by the release of relay 1 atthe end of the signal.

If the last three dots of the signal were followed by a dash, relays 38and 39 would be operated as previously explained. Relay 39 at con: tact74 closes the circuit for relay 6 which operates and at contacts 76 and78 opens the holding circuits of the relays of the first three dotgroups and the first three dash groups which thereupon release. Relay30, in releasing, opens contact thereby opening the circuit of relay 7which has not had time to operate. The relays of the last three dotgroups and of the fourth dash group remain locked up until relay 1releases during the abnormal pause between signals.

From the foregoing, it will be seen that the only possible signal orcombination of impulses which can operate the chain ofregistering relaysto bring in an alarm is the S. O. S. signal of three dots, three'dashes,and three dots, transmitted as one letter. The possibility of thissignal being duplicated by a combination of static and telegraph signalsis very remote.

Although only a particular application of the invention has beendescribed in the foregoing specification, it is apparent that thereceiver could be arranged to respond only to some signal other than anS. 0. S. call without departing from the spirit of the invention.

Having described the invention, what is thought to be new and is desiredto have protected by Letters Patent will be set forth in the appendedclaims.

What is claimed is:

1. In a receiving device, a counting apparatus, means for causing aprogressive operation of said apparatus responsive to successive spacedsignals of two kinds forming a predetermined code, an alarm, means foroperating said alarm upon the complete operation of said apparatus inresponse to said code, a second alarm, and means for operating saidsecond alarm responsive to a predetermined number of complete operationsof said apparatus.

2. In a receiving device, dot and dash counting means completelyoperable responsive to a particular dot and dash code signal only, analarm signal, means responsive to the complete operation of saidcounting means for operating said alarm signal, a second alarm signal,and means responsive to a predetermined number of complete operations ofsaid counting means for operating said second alarm signal.

3. ,In combination, -dot and dash counting means completely operableonly by dot and dash impulses in accordance with a predetermined code, astepping switch, means responsive to each complete operation of saidcounting means for advancing said switch one step, a visual signaloperated as soon as said switch is operated oil-normal, and an audiblealarm signal operated when said switch has been advanced to apredetermined position.

4. In combination, dot and dash counting means completely operable onlyby dot and dash impulses in accordance with a predetermined code, astepping switch, means responsive to each complete operation of saidcounting means. for advancing said switch one step, a visual signaloperated as soon as said switch is operated offnormal, an audible alarmsignal operated when said switch'has been advanced to a predeterm &

mined position, and ually operated means for releasing said switch atany time.

5. In combination, dot and dash counting means completely operable only,by dot and dash impulses in accordance with a predetermined code, meansfor registering the number of complete operations of said countingmeans, a, visual signal operated responsive to the registering of thefirst operation of seid counting means and an audible alarm signaloperated when a predetermined number of said operations have beenregistered.

6. In a selective code receiver, three groups oi register relays, meansfor operating each group in accordance with impulses of a predeterminedcode signal, means for insuring the sequential operation of said groupsof relays including is releasing circuit for the relays oi the firstgroup controlled by the first relay in the third group,

rea ers and e holg circuit'for the relays of said first group controlledby the last relay in the second group.

7. In a selective code receiver, three groups of register relaysarranged to be operated in sequence, means for operating each group inthird group are being operated, and contacts on the first relay of thethird group for opening said first locking circuit. I

HARRY E. HERSEEY,

